Possible to swap an 8.1L into a GMT900 truck?
09-28-2015, 10:48 PM
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Possible to swap an 8.1L into a GMT900 truck?
I'm tossing around some ideas in my head for a replacement for my 2003 2500 Suburban. I'd like to get into a GMT900 Suburban or YukonXL, but I have heard that they could use some help in the towing power dept.
Which got me thinking : how feasible would it be to swap an 8.1L into say a 2007 or 2008 GMT900 Sub or Yukon?
I know the engine transmission combination would physically fit - the Duraburb guys are swapping in Duramax/Allison powertrains by bringing the bodies up a little with spacers.
I've also read that the 8.1L basically uses the same fuel map as the LQ4 on the GMT800 trucks.
Any ideas on what the stumbling blocks might be for getting something like this to work?
Would I better off just going with a blower on a 6.0L for some more towing power?
Which got me thinking : how feasible would it be to swap an 8.1L into say a 2007 or 2008 GMT900 Sub or Yukon?
I know the engine transmission combination would physically fit - the Duraburb guys are swapping in Duramax/Allison powertrains by bringing the bodies up a little with spacers.
I've also read that the 8.1L basically uses the same fuel map as the LQ4 on the GMT800 trucks.
Any ideas on what the stumbling blocks might be for getting something like this to work?
Would I better off just going with a blower on a 6.0L for some more towing power?
09-29-2015, 06:24 PM
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If the LSx motors fit, the 8.1L fits - and the swap is relatively easy.
You'll have to make motor mounts (or adapt the GMT800 8.1L mounts) and you'll need to switch a couple wires around (cam sensor, map sensor, knock sensors) and you'll need an 8.1L flexplate, but other than that it bolts right up.
You'll need a good dyno tuner (load bearing is preferred) to tune the computer. Our 540 suburban (8.1L stroker kit) started life as a 6.0 which we tore out. Still uses the LQ4 computer, just add some fuel to match the extra displacement and away you go.
And if you want to add a blower, we're just finishing up the 2.9L whipple kit for the 8.1L engines which will require a forged bottom end (8-10psi). Here's a shot of mockup, this kit should make a casual 750hp+
You'll have to make motor mounts (or adapt the GMT800 8.1L mounts) and you'll need to switch a couple wires around (cam sensor, map sensor, knock sensors) and you'll need an 8.1L flexplate, but other than that it bolts right up.
You'll need a good dyno tuner (load bearing is preferred) to tune the computer. Our 540 suburban (8.1L stroker kit) started life as a 6.0 which we tore out. Still uses the LQ4 computer, just add some fuel to match the extra displacement and away you go.
And if you want to add a blower, we're just finishing up the 2.9L whipple kit for the 8.1L engines which will require a forged bottom end (8-10psi). Here's a shot of mockup, this kit should make a casual 750hp+
Last edited by Raylar Engineering; 09-29-2015 at 06:29 PM.
09-30-2015, 09:39 AM
#5
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I think the real question is can you afford the longer-term investment in MPG loss. 8.1's are powerful, can be made more powerful (as clearly indicated in reply above mine), but they are THIRSTY...
If you're dead set on a Suburban and it must be a tow rig, you might consider a wrecked diesel as a donor vehicle and do the other swap you mentioned. You'd have a more capable vehicle all-around.
And that's tough for me to say, because generally I'm not a diesel fan, and I love Chevy big blocks. But I also don't drag heavy trailers around, so if the mood strikes, I can sport a big block around if I felt like it, and still laugh about single-digit MPG's.
When I built a wrecker for my old shop, I gladly stuffed a Vortec 7.4 in place of a blown-and-missing 6.5TD, no worries, 12K lb truck couldn't pass a gas station but it did everything else I needed it to.
Richard
If you're dead set on a Suburban and it must be a tow rig, you might consider a wrecked diesel as a donor vehicle and do the other swap you mentioned. You'd have a more capable vehicle all-around.
And that's tough for me to say, because generally I'm not a diesel fan, and I love Chevy big blocks. But I also don't drag heavy trailers around, so if the mood strikes, I can sport a big block around if I felt like it, and still laugh about single-digit MPG's.
When I built a wrecker for my old shop, I gladly stuffed a Vortec 7.4 in place of a blown-and-missing 6.5TD, no worries, 12K lb truck couldn't pass a gas station but it did everything else I needed it to.
Richard
11-05-2015, 10:40 PM
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I think the real question is can you afford the longer-term investment in MPG loss. 8.1's are powerful, can be made more powerful (as clearly indicated in reply above mine), but they are THIRSTY...
If you're dead set on a Suburban and it must be a tow rig, you might consider a wrecked diesel as a donor vehicle and do the other swap you mentioned. You'd have a more capable vehicle all-around.
And that's tough for me to say, because generally I'm not a diesel fan, and I love Chevy big blocks. But I also don't drag heavy trailers around, so if the mood strikes, I can sport a big block around if I felt like it, and still laugh about single-digit MPG's.
When I built a wrecker for my old shop, I gladly stuffed a Vortec 7.4 in place of a blown-and-missing 6.5TD, no worries, 12K lb truck couldn't pass a gas station but it did everything else I needed it to.
Richard
If you're dead set on a Suburban and it must be a tow rig, you might consider a wrecked diesel as a donor vehicle and do the other swap you mentioned. You'd have a more capable vehicle all-around.
And that's tough for me to say, because generally I'm not a diesel fan, and I love Chevy big blocks. But I also don't drag heavy trailers around, so if the mood strikes, I can sport a big block around if I felt like it, and still laugh about single-digit MPG's.
When I built a wrecker for my old shop, I gladly stuffed a Vortec 7.4 in place of a blown-and-missing 6.5TD, no worries, 12K lb truck couldn't pass a gas station but it did everything else I needed it to.
Richard
Ok - so here's the thing: I have SERIOUSLY contemplated the diesel swap route of going with a Duramax. But I live in MA - so there is potential huge problem with getting the truck thru the inspection process. I've talked with a couple of guys who I know who run inspection stations - and I've talked with a couple of guys who have done the conversions in-state - and the way they get around it is they "know somebody".
I don't know anybody - and I'm not willing to risk all the time and money on a Duramax conversion that I might get screwed on later if somebody raises a red flag.
So it's back to gas options.
Why am I asking about the 8.1L ? Because I've spent a decent amount of time searching and searching and reading up on multiple forums - as well as talking with number of people who have towed with them extensively. I also had a GM Service manager who has experience with them over many years tell me that the 8.1L's get decent mileage compared to the 6.0's when towing.
I've also read up on a number of people who have eeked out similar mileage numbers from the 8.1L after doing things like adding headers, manifold mods - etc.
Thanks for the answer Raylar - I have seen you respond with similar information in other forums about how easy the swap is. But I have a very slight problem with your answer: I understand that the engine will be a physical bolt in to a GMT900 (2007 and up) chassis - and it will bolt up to the transmission.........
But what I'm wondering is if the ECM on the GMT900 trucks would run the 8.1L ? I understand that the ECM from the GMT800 trucks was pretty much the same in the 8.1L and the 6.0L - would the same rule apply to the later year trucks? I know they're using a different engine control computer.
If I could stick an 8.1L in front of a 6L90 I think I might help squeeze a little more fuel mileage out of it.
11-05-2015, 10:45 PM
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I live in MA. GMT800 trucks at this point are one of two things - complete rust buckets or trucks in decent shape with a crapload of mileage on them that are in need of serious restoration.
I have a GMT800 now - I like the truck , but I'd like a GMT900 better. Plus whatever route I go down - I'll be keeping the truck for a LONG time - like 10-15 years at least.
I'd rather get into a newer truck because of that.
The only really big difference or potential sticking point that I see between the GMT800 and the GMT900 is the engine control computer - and whether or not it could run the 8.1L. In the GMT800 my understanding is that the same computer was used to run the 8.1 and the 6.0.
On a 2500 series Suburban my understanding is that the frames are pretty much exactly the same between the GMT800 and GMT900. I don't anticipate any issues with the physical install. Places like Duraburb are shoving Duramax diesels into the GMT900 SUV's - so I'm pretty sure the 8.1L would fit in there easily.
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11-06-2015, 12:54 PM
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I would give Eric at Duraburb a call and see if he could get you in touch with someone who could smog the duramax swap. I did the swap myself but called Eric a few times and he was always helpful. I have an 03 yukonxl and i went with an 05 lly/allison swap, mine was a 6.0/80e. Durakon or Duraburb and dont look back!
11-06-2015, 01:34 PM
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I would give Eric at Duraburb a call and see if he could get you in touch with someone who could smog the duramax swap. I did the swap myself but called Eric a few times and he was always helpful. I have an 03 yukonxl and i went with an 05 lly/allison swap, mine was a 6.0/80e. Durakon or Duraburb and dont look back!
Ok, maybe I need to make this clear.
Been there, Done that, talked to the state DEP, talked to Eric at Duraburb, talked to two different guys in state who have them, read thru the California rules and regs (because that's what MA bases their's on) , had extensive correspondence with two different guys running state inspection stations - etc.
It's not happening.
11-06-2015, 02:59 PM
#10
Formerly ScreamingL
If the LSx motors fit, the 8.1L fits - and the swap is relatively easy.
You'll have to make motor mounts (or adapt the GMT800 8.1L mounts) and you'll need to switch a couple wires around (cam sensor, map sensor, knock sensors) and you'll need an 8.1L flexplate, but other than that it bolts right up.
You'll need a good dyno tuner (load bearing is preferred) to tune the computer. Our 540 suburban (8.1L stroker kit) started life as a 6.0 which we tore out. Still uses the LQ4 computer, just add some fuel to match the extra displacement and away you go.
And if you want to add a blower, we're just finishing up the 2.9L whipple kit for the 8.1L engines which will require a forged bottom end (8-10psi). Here's a shot of mockup, this kit should make a casual 750hp+
You'll have to make motor mounts (or adapt the GMT800 8.1L mounts) and you'll need to switch a couple wires around (cam sensor, map sensor, knock sensors) and you'll need an 8.1L flexplate, but other than that it bolts right up.
You'll need a good dyno tuner (load bearing is preferred) to tune the computer. Our 540 suburban (8.1L stroker kit) started life as a 6.0 which we tore out. Still uses the LQ4 computer, just add some fuel to match the extra displacement and away you go.
And if you want to add a blower, we're just finishing up the 2.9L whipple kit for the 8.1L engines which will require a forged bottom end (8-10psi). Here's a shot of mockup, this kit should make a casual 750hp+